1. Field of the Invention
The invention relates to a cellular phone housing which is inexpensive to manufacture and also which has high rigidity, static strength, and shock resistance even with a small thickness thereof.
The present application claims priority of Japanese Patent Application No. 2000-350242 filed on Nov. 16, 2000, which is hereby incorporated by reference.
2. Description of the Related Art
With prevalence of cellular phones in recent years, there have been more and more desires for reducing size and weight thereof. To further reduce the size and weight of the cellular phones, many methods have been developed to reduce a thickness of a housing of those cellular phones, which is, however, accompanied by a problematical decrease in rigidity and shock resistance of the housing.
To enhance the rigidity of the housing, such a method is employed by some manufactures as to use as a material of the housing, for example, a reinforced resin material filled with glass fiber or carbon fiber.
If the reinforced resin material containing such the filler is used, however, the filler has an adverse effect on a fluidity of the resin during molding, thus making it difficult to make the housing structure thin and more complicated design shapes are difficult to mold, which is a problem.
Also, a display screen is desired to be larger as more and more e-mails are being transmitted and received between cellular phones and more and more home pages are utilized thereon recently. To accommodate such a large-sized screen, a folding construction has been employed, which is however accompanied by a problem of a deteriorated strength of a hinge for connecting an upper-side housing portion and a lower-side housing portion with each other.
To solve this problem, one method is used to make the housing by die-cast metal molding so that the hinge may be kept to be strong even with a thin and light body of the housing.
The die-cast metal molded housing, however, is deteriorated in moldability if it is thin; and also burrs generated during molding thereof must be removed, which causes another problem of a deteriorated productivity, a higher cost, and a like. Further, the die-cast metal molded housing has high rigidity, so that the housing, if a relevant cellular phone is dropped, cannot absorb a shock, which is directly loaded on an internal printed board or electric elements, thus leading to a problem of increased damage to electric connections.
Thus, the prior art cellular phone housing, if it is made of a reinforced resin material containing a filler for a smaller and lighter construction, is difficult to make thin and mold into a complicated design shape, and if it is die-cast metal molded in construction in order to increase the strength of a hinge of the holding housing, accompanied processes of molding it into a thin construction and removing the burrs inevitably leads to a problem of deteriorated productivity and increased manufacturing costs; further, such the housing has a poor shock absorptive characteristic and so suffers from a problem that a shock, when it is dropped, may affect the internal board and the connections of the elements or a like.